1 2 THE HIS TOR Y OF AQUA RIA . 



anything for granted that has not been amply proved. 

 At the meeting of the British Association at Cam- 

 bridge, in 1833, Dr. Daubeny showed that plants 

 when in water (and aquatic species particularly) gave 

 out oxygen and absorbed carbon under the influence 

 of light. After detailing his experiments he expressed 

 his opinion an opinion which has since then not only 

 been proved true, but which is universally accepted 

 that " he saw no reason to doubt that the influence of 

 the vegetable might serve as a complete compensation 

 for that of the animal kingdom." An old proverb 

 says : "A child on a giant's shoulders sees farther than 

 the giant." It is only the superficial who smile at 

 the strenuous efforts of great intellects to attain unto 

 a knowledge of those principles which we now regard 

 as self-evident and incapable of contradiction. There 

 is an evolution of knowledge as there is of animal 

 and vegetable life. Daubeny saw dimly less than 

 half a century ago what every teacher in physical 

 geography now imparts to his class that the oxygen 

 generated in the virgin forests of the Amazons valley 

 may be brought by the wind to bring health to 

 the fetid streets and alleys of crowded European 

 cities, and that in return the carbonic acid breathed 

 forth from our over-populated towns may be carried 

 on the " wings of the wind," to be eventually absorbed 

 by the incalculable stomata which crowd the under 

 surfaces of the leaves in the same forest-clad region ! 

 The labours of an unassuming but true naturalist, 



